The present invention relates to a device in drums designed to operate Venetian blinds of the kind comprising slats supported by ladder cords. The operating drum generally comprises a cylindrical housing having a cavity for reception therein of a blind actuating or tilting shaft. The housing is formed with means for fastening the ladder cord side strands.
Venetian blind operating drums must meet strict operating requirements inasmuch as they must function reliably when one wishes to re-set the blind slat tilting positions to change the amount of light admitted through the blind. Specifically, it must be possible to attach the ends of the ladder cord side strands swiftly and securely to the operating drum.
A number of different constructions of ladder cord drums have appeared in recent years, none of which are entirely satisfactory. In accordance with one construction, a metal tongue is pressed against overlapping ends of ladder cord side strands for fastening the side strands to the drum. This construction, however, has the disadvantage that the fastening of the side strands to the drum is not entirely reliable and that after some time of use, the metal tongue may dislodge itself from the drum. Another disadvantage of existing ladder and drums is that end parts of the ladder cord side strands protrude from the drum, which may be the cause of certain complications.
Attempts have also been made to form an operating drum having slits in which to insert the ends of the ladder cord side strands alone or in combination with fastening pins. This manner of fastening the ladder cord, however, is not entirely satisfactory, since this manner of attachment complicates the fastening operation.
There exists therefore a need for an advancement in the art that overcomes the deficiencies discussed above.
It is an object of the present invention to provide a novel ladder cord operating drum.
It is also an object of the present invention to provide a novel ladder cord operating drum for engaging and retaining a ladder cord.
It is a further object of the present invention to provide a novel ladder cord operating drum having tongues for engaging and retaining a ladder cord.
It is a further embodiment of the present invention to provide a novel ladder cord operating drum for engaging, retaining and protectively receiving a ladder cord end.
These and other objects, features, and advantages of the present invention will become apparent upon consideration of the following detailed description of the invention and the accompanying drawings.